Disposable, pre-packaged device for conducting immunoassay procedures

ABSTRACT

A disposable, pre-packaged device for conducting an immunoassay procedure that results in the production of separable liquid and solid phases. The device includes a cup having an inlet and presenting a liquid phase receiving chamber. An absorbent for liquid phase materials is in the chamber and a series of ribs hold the absorbent away from the walls of the chamber providing a breathing space extending around the absorbent. A porous capture media element for capturing and displaying solid phase products of the procedure is disposed adjacent the inlet of the device in fluid communication with the absorbent so that in operation the absorbent promotes flow of liquid phase through the capture element. A lid element is mounted on the cup adjacent the inlet and the lid and the cup are held together by welding of annular flanges. The lid element includes an elongated cylindrical member extending through the inlet and defining a throat for directing flow of liquid phase onto the capture media. The cylindrical member has an annular surface at its inner end for contacting the porous capture media and holding it in tight fluid communication with the absorbent. A vent hole is provided in the lid flange to facilitate venting of the breathing space. The vent hole and the throat opening are disposed in a single plane so that a single planar coil element may be used to keep out contamination during storage and shipment.

This is a continuation of copending application Ser. No. 07/107,240filed on Oct. 29, 1987 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention related to device for conducting immunoassayprocedures. In particular, the invention relates to disposable,pre-packaged devices which are particularly suitable for conduct ofdiagnostic procedures based on immunological reactions at remote sitessuch as physician's offices and homes of users.

2. Description of the Prior Art

Since the important discovery of Millstein and Kohler reported in Nature256: 495-497, 1975, the development of highly sensitive and specificimmunoassay procedures has proceeded at a rapid pace. In fields such asclinical medicine, forensic sciences, environmental quality testing,food quality assurance, drug testing and other related areas, it hasbecome possible to determine the presence and/or amount of tracesubstances in test samples even when such substances are present in verylow concentrations in the order of parts per million, or even less. Thedevelopment of non-radioactive labels or markers, such as enzyme colorformers, has facilitated the use of immunoassay diagnostic proceduresoutside of laboratory settings and in remote sites such as physician'soffices and even the homes of the users. In the physician's office,immunological procedures are useful to provide rapid, simple assayswhich may be performed while the patient is still in the office so thatthe diagnosis can be accomplished without delay and treatment institutedduring a single visit. Without such simple assays, it has often beennecessary for the physician to collect a sample from the patient duringa first visit and to have the sample analyzed by a clinical laboratorywith the results reported back to the physician by the laboratory at alater time. In the meanwhile, the patient was sent home and was requiredto return for a second visit with the physician in order to receiveappropriate treatment and/or medication. Manifestly, such delay wasinefficient and inappropriate and in some cases could even be lifethreatening.

Home testing has became desirable to facilitate testing by the consumerin the privacy of his or her own home. The results of such testingmight, for example, indicate the necessity or lack of necessity of avisit to the physician. Examples of useful test for the "at home" marketinclude tests for pregnancy, ovulation, streptococcus infection andother infections which are detectable by analysis of urine, saliva orother appropriate test samples.

For remote site testing, assuming appropriate sensitivity andspecificity can be achieved, there are at least three other requirementsfor practical assay procedures. The first of these desirable factors isspeed in that the assay must be performed in an acceptably short periodof time, the shorter the better. Stability is also a desirable featurein that the components of the assay should be stable for an extendedperiod of time without refrigeration or special handling and the assayresults or readouts should be sufficiently stable so that theinterpretation may be confirmed even several days after the initial testis performed. Finally, from a commercial view point it is desirable thatthe test be as simple as possible requiring only minimal or noinstrumentation and precluding mistakes and poor performance resultingin incorrect interpretations.

Immunoassay kits employing enzyme markers are presently commerciallyavailable today for determining pregnancy and ovulation in thephysician's office and in the home of the user. The technical componentsgenerally required in such kits are (1) a solid phase bearingimmobilized antibody, (2) an enzyme labelled antibody, (3) a rinsesolution (in some cases this may be the users tap water), and (4) asubstrate for the enzyme. A typical procedure is that the sample ismixed with the solid phase and incubated (with or without a subsequentrinse step) and then the sample is discarded, the solid phase is thencontacted with the enzyme labelled antibody and incubated. Thereafterthe solid phase is rinsed and contacted by the substrate. After a periodof time (ca 5 minutes) the color of the solid phase is observed. Onesuch assay is described in U.S. Letters Pat. No. 4,632,901.

Enzyme labelled immunoassays are not without their own drawbacksresulting from the instability of some enzyme systems, the number of kitcomponents and the complexity of the procedure. Such shortcomings havebeen addressed in the co-pending application of Cole, Davis and Sigillo,entitled "Metal Sol Capture Immunoassay Procedure, Kit For Use Therewithand Captured Metal Containing Composite," and filed Oct. 7, 1987,(serial number not yet assigned), which application is assigned to theassignee of the present application. In said co-pending Cole et al.application, a metal particle label is utilized and a collectible, solidphase, metal containing composite is formed. The composite is collectedon a filter element or the like where the presence of analyte in theoriginal sample is determined or detected by evaluating, through directvisual examination, the presence of metal in the collected solid phasecomposite.

One of the difficulties encountered in the development of test devicesfor remote site testing is the provision of a practical pre-packageddisposable device to facilitate efficient, relatively inexpensive testprocedures. This, of course, requires a device which is inexpensive toconstruct, which has a shelf life appropriate to the commercial use ofthe device, which is protected against contamination during handling,and which may be simply and readily utilized when the appropriate timearises. The device illustrated in the '901 patent mentioned aboveaddresses some of these problems and is available commercially; however,the device has a number of deficiencies including retarded flow of fluidinto the absorbent. It is believed that such flow problems were perhapsalleviated to some degree by the provision of notched vertical ventinggrooves in the periphery of the absorbent plug. Such venting groovesfacilitated venting of the device during use through small portsprovided near the bottom of the container. Of course, liquid couldescape through such vent ports creating a messy operation, sealing priorto use was difficult and the manufacture of the grooved absorbent plugsis a relatively expensive operation.

Other prior single test devices are illustrated in U.S. Letters Pat.Nos. 4,366,241 and 4,623,461. However, these devices are of limitedapplication and also have excessive complexity.

SUMMARY OF THE INVENTION

The present invention provides relief from many of the shortcomings ofthe prior art devices described above. In this regard, the inventionprovides a simplified, pre-packaged, disposable test device wherein theliquid sample flows freely through a porous capture media means whereproducts of the procedure are captured and displayed. The devicecomprises structural elements which facilitate assembly, pre-packagingand sealing of the device prior to intended use.

In accordance with the present invention, a disposable, prepackageddevice for conducting an immunoassay procedure is provided. The devicecomprises cup means defining a chamber for receiving liquid residuesfrom the procedure. The cup means includes structure defining a liquidinlet communicating with the chamber. Absorbent means are disposed inthe chamber for promoting flow of liquid into the chamber and spacermeans are provided in the chamber for holding the absorbent means awayfrom the inner walls of the chamber to present a breathing spacecommunicating with the inlet. The breathing space extends essentiallyentirely around the absorbent means to facilitate venting and thus flowof fluid into the absorbent during the conduct of the test procedure.The device preferably includes porous capture media means for capturingand displaying products of the procedure, such porous capture mediameans being disposed adjacent the inlet of the device and in fluidcommunication with the absorbent means. Additionally, the devicepreferably includes a lid element including means defining a throatdisposed to extend through the inlet of the cup means for directing flowof liquid assay reaction media through the inlet and onto the porouscapture capture means.

To facilitate manufacture and assembly of the device, the lid elementpreferably includes means defining a pusher member for contacting theporous capture media means and pushing the latter toward the absorbentmeans and into fluid communication therewith. Also, to facilitateassembly the device preferably includes an annular flange on the lidelement extending around the throat and a mating, corresponding annularflange on the cup means extending around the inlet Means are providedfor securing the flanges together in mated relationship with the throataligned with the inlet.

To further facilitate pre-packaging of the device, the lid elementflange includes means defining at least one vent hole disposed in fluidcommunication with the breathing space of the cup device andfacilitating venting of the latter to the atmosphere. Such constructionenables the use of a removable sealing means closing the throat and thevent hole to thereby prevent introduction of foreign material into thedevice prior to its intended use. In this regard, in a preferredembodiment of the invention the external openings of the vent hole andof the throat are disposed in the same plane and the sealing meanscomprises a single planar element, such as a piece of metal foil,disposed in sealing relationship to the openings.

In a most desirable commercial form of the invention, the deviceincludes a lid element mounted on the cup means adjacent the inlet andhaving a centrally disposed cylindrical member extending through theinlet and defining a throat positioned for directing flow of liquidassay medium through the inlet and onto the capture media means. Thecylindrical member has an annular surface at its free end disposed forcontacting the porous capture media means and pushing the latter towardthe absorbent means and into said fluid communication. In this form ofthe invention, the lid element also includes an annular flange extendingaround the cylindrical element and the cup means includes a mating,corresponding annular flange extending around the inlet. Means areprovided for securing the flanges together in mated relationship withthe throat aligned with the inlet and with the annular surface disposedin pushing relationship relative to the capture means.

In one preferred form of the invention, the porous capture media meanscomprises a filter element having pores of a size to prevent passage ofdesired reaction products. In another preferred form of the invention,the porous capture media means comprises a microporous membrane to whichis bound an immunoreactive substance that is specifically reactive inthe desired reaction. In either case, the device preferably includes ahydrophobic, porous separator element interposed between the porouscapture media means and the absorbent means to insure completeseparation between the captured reaction product on the capture mediameans and the liquid phase which has been drawn into the absorbentmeans.

In a particularly preferred form of the invention, the cup meanscomprises a generally cylindrical wall surrounding the chamber, theabsorbent means comprises an elongated element which is generallycircular in cross-sectional configuration, and the spacer meanscomprises a plurality of generally rectangularly shaped wing membersextending radially inwardly from the cylindrical wall of the cup means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a disposable, pre-packaged device forconducting an immunoassay procedure, which device embodies theprinciples and concepts of the present invention;

FIG. 2 is a cross-sectional view taken along view line 2--2 of FIG. 1;

FIG. 3 is a cross-sectional view of the device of the invention takenalong view line 3--3 of FIG. 2;

FIG. 4 is an elevational, exploded view of the device illustrating therelationship between the various components of the assembled device; and

FIG. 5 is a cross-sectional view of an alternative form of the lidelement useful in connection with an alternative device embodying theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The concepts and principles of the present invention are embodied in adisposable, pre-packaged device 10 which is useful for conducting animmunoassay procedure. The type of procedure utilized is not importantfor purposes of the present invention other than that the device may beused to facilitate any sort of procedure which results in the productionof a collectible phase which incorporates a tag of some sort to indicatea positive or negative test results. Generally speaking, the device 10of the present invention will be utilized in connection with procedureswhich employ a visually detectable colored or color forming tag such asan enzyme or metal sol particle tag. However, it is within the perceivedusefulness of the invention that the device might well be employed inconnection with procedures wherein a reactant is tagged with aninstrument detectable tag such as a radioactive isotope, a fluorescentmaterial or a chemiluminescent material.

The device 10, in its preferred form, includes a cup member 12encompassing a chamber 14 for receiving liquid residues from animmunoassay procedure. Absorbent means in the form of an elongatedabsorbent plug 16, which is generally circular in cross-sectionalconfiguration, is disposed in chamber 14 for the purpose of promotingflow of liquid into the chamber, as will be explained in more detailhereinbelow. Cup 12 includes structure at its upper end defining aliquid inlet opening 17 that is in fluid communication with the interiorof chamber 14.

Device 10 also includes porous capture media means in the form of acircular element 18 for capturing and displaying products of animmunoassay procedure, a function which will be described in greaterdetailed hereinafter. Element 18 is disposed adjacent inlet opening 17and operationally is in fluid communication with absorbent plug 16during the conduct of the immunoassay procedure. A circular,hydrophobic, porous separator element 20 may be interposed betweenelement 18 and absorbent plug 16 to facilitate essentially completeseparation of said reaction products and liquid residues. Again, thefunction and characteristics of separator 20 will be described ingreater detail hereinbelow.

Cup 12 comprises a cylindrical wall 22 which surrounds chamber 14. Aplurality of elongated, generally rectangular wing members 24 extendradially inwardly from wall 22, as can best be seen in FIG. 3. Theinnermost edge of each member 24 contacts the outer periphery ofabsorbent plug 16, and thus, wing members 24 present spacer meansdisposed in chamber 14 for holding absorbent plug 16 away from the innersurfaces of wall 22 to provide a breathing space 26 which communicateswith inlet 17 and extends essentially entirely around thecircumferential periphery of absorbent plug 16.

Cup 12 is also provided with an annular flange 28 which extends aroundinlet 17. Device 10 further includes a generally annular lid element 30having a mating, corresponding flange 32. Element 30 also comprises acylindrical member 34 having an annular surface 36 at its free end. Ahollow, generally frustoconical segment 38 interconnects cylindricalmember 34 and flange 32. Together, cylindrical member 34 andfrusto-conical segment 38 present means defining a throat 40 whichextends through inlet 17. Functionally, throat 40 is positioned fordirecting the flow of liquid reaction medium onto the porous capturemedia element 18.

Flange 28 extends around inlet 17 and flange 32 extends around throat40. Flanges 28 and 32 are mating, corresponding flanges, and when thedevice is assembled as illustrated in FIG. 2, annular surface 36 is intight, pushing contact with respect to porous capture media element 18.In this connection, it is to be understood that absorbent plug 16 ispreferably somewhat resilient and compressible, and during assemblysurface 36 contacts element 18 and pushes the latter toward absorbentplug 16 and into tight fluid communication therewith by way of the poresof separator element 20.

During assembly, flanges 28 and 32 are held together in matedrelationship with throat 40 aligned with inlet 17 and With annularsurface 36 held tightly against element 18 in pushing relationshipthereto. Accordingly, cylindrical member 34 and its free annular surface36 present a pusher element disposed in pushing relationship relative tothe porous media capture element 18. Manifestly, during assembly, theflanges 28 and 32 are held together by a mechanical device (notillustrated) and while so held together, the same are preferablysonically welded. To facilitate such procedure, means in the nature ofannular sonic weld energy director beads 42 are initially provided onflange 28 to facilitate the sonic welding process. However, it is to beunderstood that sonic welding and beads 42 are not critical aspects ofthe present invention. And in fact, there are alternative methods forsecuring flanges 28 and 32 together, such alternative methods beingconventionally used and known to those skilled in the art.

A pair of spaced, opposed vent holes 44 are provided in flange 32, ascan best be seen in FIG. 2. Vent holes 44 are disposed in fluidcommunication with breathing space 26 via the annular portion 17a ofinlet 17 that surrounds cylindrical member 34 and frusto-conical segment38 of lid element 30. Vent holes 44 are thus available to facilitateventing of breathing space 26 to the atmosphere surrounding the device10 during the conduct of an immunoassay procedure utilizing device 10.

As can best be seen viewing FIG. 2, the external openings of vent holes44 and the external opening of throat 40 are all disposed in a singleplane extending along the upper surface of flange 32. Sealing means inthe nature of a single planar foil element 46 is removably affixed tothe upper surface of flange 32 using conventional adhesive means. Foilelement 46 is provided with a conventional tab 46a to facilitate removalof element 46 from the upper surface of flange 32 by peeling.Accordingly, foil element 46 closes throat 40 and vent holes 44 tothereby prevent introduction of foreign material into the device priorto its intended use and yet foil element 46 is readily removable by theuser at the time the device 10 is to be used.

Cup 12 and lid element 30 may be constructed of plastic or glass or anyother suitable material, and these elements may preferably be made by aninjection molding procedure utilizing a thermoplastic material. The onlylimitation on the materials of construction being that the same must beinert to the reactants and reaction products.

Absorbent plug 16 is an absorbent member having capillary passagesextending therethrough in a diversity of directions which are bothtransverse to and generally parallel to the surfaces at the upper andlower ends of plug 16. There are a number of materials which are wellknown to those of ordinary skill in the art to which this inventionpertains that may be used to construct absorbent plug 16. Such materialsinclude hydrophillic polymers, particulate absorbents, glass fibers,cotton fibers, cellulose fibers, wood pulp and/or sponge. Othermaterials which may find use as plug 16 include polysaccharides, forexample cellulosic materials, such as paper and cellulose acetate.Cellulose acetate fibers arranged in the same manner as in a cigarettefilter may be utilized to construct absorbent plug 16. Another usefulmaterial is the absorbent material used in a tampon. A particularlyuseful material is a cellulose acetate fiber Transorb plug asmanufactured by American Filtrona Co. In any event, the importantfeatures of the materials useful in the construction of plug 16 aresimply that the same be capable of absorbing aqueous materials and thatthey possess sufficient structural integrity to permit the initialconstruction of the device. Further useful absorbent materials aredisclosed, for example, in U.S. Letters Pat. Nos. 4,246,339; 4,623,461;4,632,901; and 4,366,241.

Separator element 20 simply serves the purpose of separating porouscapture media element 18 from absorbent plug 16 to assure that liquid atthe upper surface of absorbent plug 16 does not interfere with theresults to be evaluated at the surface of element 18. In this respect,separator element 20 should preferably be constructed of a hydrophobic,porous material, such as, for example, the hydrophobic, porous non-wovenrayon material disclosed in U.S. Pat. No. 4,246,339 or the porouspolyethylene or other material which does not bind receptornon-specifically, such as is disclosed in International Publication No.WO85/05451 (International Application No. PCT/US85/00870). A porouspolyester material available commercially in sheet form from PorexTechnologies is a particularly useful material. Other useful materialsinclude glass fiber layers (Whatman) and porous plastic layers (Porex orPellon).

With regard to the porous capture media element 18, this element maytake any one of several different forms depending on the type ofimmunoassay procedure which is utilized. For example, if the immunoassayinvolves an ELISA technique, element 18 may be a membrane having aco-reactant for the reagent to be assayed in the test liquid sampleimmobilized on the internal and external surfaces thereof. Suchmembranes are utilized in the procedures disclosed in U.S. Letters Pat.No. 4,246,339 and in said International Publication no. WO85/05451. Themembranes useful in connection with such procedure are fully disclosedand described in U.S. Letters Pat. No. 4,340,479. Manifestly, methodsfor binding immunoreactants to such membranes are well known to thoseskilled in the art to which the present invention pertains.

In another form of the invention, the porous capture media element 18may be composed of such things as glass fiber filters (Whatman GF/A),regenerated cellulosic membranes (Schleicher and Schuell) andmicroporous membranes (Millipore MF series membranes HAWP, SSWP, SMWPand SCWP with pore sizes of 0.45, 3, 5 and 8 microns respectively). Allof these materials have been successfully utilized for capturing andcollecting a solid phase product resulting from an immunoassayprocedure. In particular such materials have been found useful forcapturing the collectible, solid phase, metal containing composite whichresults from the immunoassay procedure described in said co-pending andco-assigned application of Cole et al. Manifestly, in such process theporous capture media element simply comprises a filter element havingpores of a size to prevent passage of desired reaction products.Accordingly, the desired reaction products accummulate on the surface ofthe element and are available there for visual inspection.

Another capture material which is potentially useful as element 18 is amicroporous member to which avidin has been linked whereby biotinylatedreaction materials may be captured.

Manifestly, the capture matrices disclosed in said co-pending Cole etal. application are all useful in connection with the present invention,as are the absorbent materials and separator materials disclosedtherein. Accordingly, the entirety of the disclosure of said co-pendingapplication of Cole et al. is hereby specifically incorporated herein byreference.

In the operation of device 10, immunoreagents are contacted with asample and the mixture is allowed to incubate for a period of time, allas is well known to those skilled in the immunoassay art. After asufficient incubation period, the reaction mixture is simply pouredthrough throat 40 and onto element 18. Capillary action in absorbentplug 16 promotes flow of liquid through element 18 and through separator20, and thus the liquid phase is separated from the solid phase byelement 18. Air or other gases originally present in plug 16 are readilyvented through space 26 and upwardly through vent holes 44. Thisfacilitates the absorbent action in absorbent plug 16, since with thestructure provided by the present invention, there is no substantialpossibility of entrapping air within the device to impede the flow offluid into absorbent plug 16. To insure complete separation between theliquid phase in absorbent plug 16 and the solid phase on the surface ofporous media capture element 18, a rinse solution may be poured throughthroat 40 after the reaction mixture has been introduced. Manifestly,formation of coloration on the surface of element 18 provides an almostinstantaneous indication of the results of the assay, whether the sameinvolves a metal sol tag in accordance with the procedure disclosed insaid co-pending Cole et al. application, or an enzyme tag and animmobilized antibody, such as is disclosed in U.S. Letters Pat. No.4,407,943.

It will be readily apparent to those of ordinary skill in the art, thatwhile the device of the present invention has been described inconnection with certain specific immunoassay procedures, the same mayalso be utilized in connection with other immunoassay procedures thatinvolve a liquid phase reaction and production of a labelledimmunoreaction product that is capturable on a porous media captureelement, either by a filtration process or chemical linkage. In thisregard, element 18 may be a filter element having pores of a size toprevent passage of a desired reaction products, or a porous element,such as a microporous membrane, to which is bound an immunoreactivesubstance that is specifically reactive in the desired immunoassayreaction.

Sealing element 46 may simply be a formed piece of an impermeable sheetmaterial. Preferably element 46 may be a piece of metal foil which isremovably attached by an adhesive to the upper surface of flange 32 inclosing relationship to throat 40 and vent holes 44. In this regard, theattachment may preferably be by way of an adhesive material whichpermits foil 46 to simply be peeled away from the top of device 10utilizing tab 46a to thereby to expose throat 40 and vent holes 44.While foil 46 remains in place, all internal areas of device 10 areprotected against inadvertent introduction of foreign materials.Accordingly, the transportability, shelf life and storability of thedevice is enhanced.

With reference to FIG. 5, an alternative lid element 130 is illustrated.Lid element 130 is generally the same as lid element 30 except that itis designed so that throat area 140 is frusto-conical in shape. Thus,the liquid flowing through throat 140 is channeled into a much smallerflow area and therefore contacts a much smaller area of porous capturemedium 18. This results in a concentration of the tagged reactionproduct captured on medium 18 and a resultant enhancement of coloration.Lid element 130 may be used to replace lid element 30, particularly inconnection with the form of the invention where the porous capturemedium 18 is a simple filter and the tag is a metal sol particle asdisclosed in said co-pending Cole et al. application.

We claim:
 1. A disposable, pre-packaged device for conducting animmunoassay procedure which results in the production of separableliquid and solid phases, said device comprising:a cup means defining anelongated chamber for receiving the liquid phase from said procedure,said cup means comprising a cylindrical wall extending around saidchamber, a closure wall at one end of the chamber and a liquid inletcommunicating with the chamber; a generally cylindrically shapedabsorbent plug disposed entirely within the chamber for absorbing saidliquid phase, said plug having a lower surface resting on said closurewall, a circumferential peripheral surface extending therearound and anupper flat surface disposed in alignment with said inlet; a porouscapture media means for capturing and displaying a solid phase separatedfrom said liquid phase, said porous capture media means being disposedbetween said inlet and said flat surface and being in fluidcommunication with said absorbent plug via said flat surface, wherebysaid absorbent plug promotes flow of liquid phase through said capturemedia means during conduct of an immunoassay procedure; and a spacermeans in the chamber holding the peripheral surface of the absorbentplug away from the cylindrical wall to thereby present an annularbreathing space communicating directly with the peripheral surface ofthe absorbent plug and extending essentially entirely around saidperipheral surface, said cup means including a vent hole adjacent saidinlet in communication with said space to facilitate venting of theabsorbent plug via said peripheral surface and said space as the plugabsorbs a liquid phase.
 2. The invention of claim 1, wherein said plugis generally circular in cross-sectional configuration and said spacermeans comprises a plurality of general rectangular shaped wing membersextending radially inwardly from said cylindrical wall.
 3. A device asset forth in claim 1, wherein said porous media means comprises a filterelement having pores of a size to prevent passage of desired reactionproducts.
 4. A device as set forth in claim 3, comprising a porousseparator element interposed between the porous means and the flatsurface of the absorbent plug.
 5. A device as set forth in claim 4,wherein said separator element is constructed of a hydrophobic material.6. A device as set forth in claim 1, wherein said porous media meanscomprises a microporous membrane to which is bound an immunoreactivesubstance that is specifically reactive in the desired reaction.
 7. Adevice as set forth in claim 6, comprising a porous separator elementinterposed between the porous mean and the flat surface of the absorbentplug.
 8. A device as set forth in claim 7, wherein said separatorelement is constructed of a hydrophobic material.
 9. A device as setforth in claim 1, comprising a lid element mounted on the cup meansadjacent the inlet and having a centrally disposed, elongatedcylindrical member extending through the inlet, said element having anopening extending through the cylindrical member for directing flow ofliquid assay reaction medium through the inlet and onto the capturemeans.
 10. A device as set forth in claim 9, wherein said lid elementincludes an annular flange extending around said opening and said cupmeans includes a mating, corresponding annular flange extending aroundsaid inlet, said device including means for securing the flangestogether in mated relationship with the opening aligned with the inlet.11. A device as set forth in claim 10, wherein said vent hole isdisposed in said lid element flange.
 12. A device as set forth in claim11, comprising removable sealing means closing the opening and the venthole to thereby prevent introduction of foreign material into the deviceprior to intended use.
 13. A device as set forth in claim 12, whereinthe external portions of the opening and the vent hole are disposed in acommon plane and said sealing means comprising a single planar elementdisposed in sealing relationship to said external portions.
 14. A deviceas set forth in claim 9, wherein said cylindrical member includes apusher segment for contacting said capture means and exerting a pushingforce against the latter to hold the capture means and the plug in saidfluid communication.
 15. A device as set forth in claim 14, wherein saidlid element includes an annular flange extending around said opening,and said cup means includes a mating, corresponding annular flangeextending around said inlet, said device including means for securingthe flanges together in mated relationship with the opening aligned withthe inlet and with the pusher segment disposed in said contactingrelationship relative to the capture means.
 16. A device as set forth inclaim 15, wherein said pusher segment is cylindrical and has an annularsurface at its free end disposed for contacting the porous capture mediameans, said opening extending through the cylindrical pusher segment.17. A device as set forth in claim 15, wherein said vent hole isdisposed in the lid element flange.
 18. A device as set forth in claim17, comprising removable sealing means closing the opening and the venthole to thereby prevent introduction of foreign material into the deviceprior to intended use.